KPop/K-pop is just a genre of music (Korean pop music)
So I'm not sure what is wrong with that... Why do I need to attach some documentary evidence for the genre of music?
The full message from Resolution Center:
Guideline 4.1 - Design - Copycats
Your app or its metadata appears to contain misleading content.
Specifically, your app includes content that resembles KPop without the necessary authorization.
Next Steps
You may attach documentary evidence in the App Review Information section in App Store Connect. In accordance with section 3.2(f) of the Apple Developer Program License Agreement, you acknowledge that submitting falsified or fraudulent documentation can result in the termination of your Apple Developer Program account and the removal of your apps from the App Store. Once Legal has reviewed your documentation and confirms its validity, we will proceed with the review of your app.
Alternatively, please remove the third-party content from your app and its metadata.